1. Field of the Invention
The present invention relates to an absorbent article for absorbing body fluids and exudates, such as urine. More particularly, the present invention relates to absorbent garments, such as disposable diapers and adult incontinence garments, which are configured to absorb body exudates while maintaining or improving the health of the wearer""s skin.
2. Description of the Related Art
Many known absorbent article configurations employ absorbent materials located between a liquid pervious topsheet and a liquid impermeable backsheet. Such backsheets are well suited to prevent the migration of liquid waste from the absorbent materials to the outer garments of a wearer. Unfortunately, the use of such articles and, in particular, such articles which include a liquid and vapor impermeable backsheet can result in a high degree of humidity within the diaper when in use which may increase the temperature of the wearer""s skin and result in relatively high skin hydration levels. Such conditions can lead to a reduction in the health of the wearer""s skin. For example, the occlusive, moist environment inside absorbent articles incorporating such backsheets can promote the viability of microorganisms, including Candida albicans, which can undesirably lead to the onset of dermatitis such as what is commonly referred to as diaper rash.
Moreover, the liquid pervious topsheets on such articles have typically been constructed of nonwoven materials such as spunbond polyolefin materials. Unfortunately, such materials do not always provide a soft, nonabrasive contact with the skin. In particular, during continuous use of absorbent articles containing such topsheets, the wearer""s skin can become quite irritated and red particularly in the presence of urine and feces. The abrasion resulting from such topsheets and the presence of urine and feces can also undesirably lead to the onset of dermatitis.
Diaper dermatitis can afflict almost every infant at some time during the diaper wearing years. The most severe form of this condition is usually caused by secondary infection with the fungi Candida albicans. Although other factors influence the pathogenesis of this fungi, one critical factor is the relative humidity within the diaper which is directly related to the occlusion or semi-occlusion of the diaper area.
In order to reduce the humidity level within diapers, breathable polymer films have been employed as outer covers for absorbent garments, such as disposable diapers. The breathable films are typically constructed with micropores to provide desired levels of liquid impermeability and air permeability. Other disposable diaper designs have been arranged to provide breathable regions in the form of breathable panels or perforated regions in otherwise vapor-impermeable backsheets to help ventilate the garment.
Moreover, to prevent body exudates from contacting the wearer""s skin, the caregiver often applies skin protective products directly to the skin of the wearer before positioning the article on the wearer. Such products have included petrolatum, mineral oil, talc, corn starch, or various other commercially available rash creams or lotions. This procedure typically involves the caregiver applying the products to their hand and then transferring the products to the wearer""s skin.
To eliminate the caregiver from contacting the products and to reduce skin abrasion and improve skin health, some conventional absorbent articles have included lotion formulations applied to the topsheet such that, in use, the formulations transfer to the skin or provide lubricity thereby reducing the friction between the topsheet and the skin. However, conventional lotion formulations have been unstable and tended to migrate away from the surface of the topsheet into the topsheet and absorbent core of the absorbent articles leaving less on the surface to transfer to the skin or provide the reduced abrasion. This migration problem is particularly evident at higher temperatures such as those at the skin surface in use or those in typical storage conditions in warm climates.
Conventional absorbent articles, such as those described above, have not been completely satisfactory. For example, articles which employ perforated films or breathable panels can exhibit excessive leakage of liquids from the article and can excessively soil the wearer""s outer garments in the regions of the perforations or panels. In addition, when the absorbent material of the article becomes loaded with liquid, the wet absorbent can block the escape of moisture from the wearer""s skin. Such absorbent garment designs have not been able to maintain a high level of breathability when wet to sufficiently reduce the hydration of the wearer""s skin.
Moreover, lotions which have been incorporated on the topsheets of such articles have migrated such that a less effective amount has been applied to the wearer""s skin or been located between the skin and the topsheet in use. Thus, large amounts of such lotions have been required to be added to the topsheet to deliver the skin benefit. As a result, the wearer""s skin has remained susceptible to rashes, abrasion and irritation. Accordingly, there remains a need for absorbent articles which maintain or improve skin health.
In response to the difficulties and problems discussed above, new disposable absorbent articles which maintain or improve the health of the wearer""s skin have been discovered. Such absorbent articles may have a high air exchange rate when wet, maintain skin temperature when wet, have reduced levels of skin hydration, include a lotion formulation or treatment composition which provides a skin health benefit, and/or have a reduced viability of microorganisms.
When employed in the present disclosure, the terms xe2x80x9ccomprisesxe2x80x9d, xe2x80x9ccomprisingxe2x80x9d and other derivatives from the root term xe2x80x9ccomprisexe2x80x9d are intended to be open-ended terms that specify the presence of any stated features, elements, integers, steps, or components, but do not preclude the presence or addition of one or more other features, elements, integers, steps, components, or groups thereof.
As used herein, reference to xe2x80x9cair exchangexe2x80x9d refers to the transfer of air and, in particular, humid air from the interior of an absorbent article, when in use on a wearer, to the exterior of the absorbent article (ambient atmosphere) which allows drier ambient air to move into the absorbent article.
As used herein, a substantially liquid impermeable material is constructed to provide a hydrohead of at least about 60 cm (centimeters), desirably at least about 80 cm, and more desirably at least about 100 cm. A suitable technique for determining the hydrohead value is the Hydrostatic Pressure Test which is described in further detail herein below.
As used herein, a substantially vapor permeable material is constructed to provide a water vapor transmission rate (WVTR) of at least about 100 g/sq.m/24 hr, desirably at least about 250 g/sq.m/24 hr, and more desirably at least about 500 g/sq.m/24 hr. A suitable technique for determining the WVTR value is the Water Vapor Transmission Rate Test which is described in further detail herein below.
As used herein, the term xe2x80x9cviscosityxe2x80x9d refers to the viscosity in centipoise determined according to ASTM D3236, entitled xe2x80x9cStandard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials.xe2x80x9d
As used herein, the phrase xe2x80x9cmelting pointxe2x80x9d refers to the temperature at which the majority of the melting occurs, it being recognized that melting actually occurs over a range of temperatures.
As used herein, the phrase xe2x80x9cmelt point viscosityxe2x80x9d refers to the viscosity of the formulation at the temperature at which the majority of the melting occurs, it being recognized that melting actually occurs over a range of temperatures.
As used herein, the phrase xe2x80x9cpenetration hardnessxe2x80x9d refers to the needle penetration in millimeters according to ASTM D 1321, xe2x80x9cNeedle Penetration of Petroleum Waxes.xe2x80x9d Lower needle penetration hardness values correspond to harder materials.
As used herein, the term xe2x80x9cz-direction migration lossxe2x80x9d refers to the value obtained when subjecting an absorbent article having a lotion formulation on the bodyfacing surface thereof to the Z-Direction Lotion Migration Test set forth below.
As used herein, the term xe2x80x9ccd-direction migration lossxe2x80x9d refers to the value obtained when subjecting an absorbent article having a lotion formulation on the bodyfacing surface thereof to the CD-Direction Lotion Migration Test set forth below.
In one aspect, the present invention relates to an absorbent article which comprises an absorbent, a front waist section, a rear waist section and an intermediate section which interconnects the front and rear waist sections. The absorbent article defines a Wet Air Exchange Rate of at least about 190 cubic centimeters per minute calculated according to the Tracer Gas Test set forth herein. In a particular embodiment, the article defines a Wet Air Exchange Rate of at least about 200, desirably at least about 225 and more desirably at least about 250 cubic centimeters per minute calculated according to the Tracer Gas Test. The absorbent article may further define a Dry Air Exchange Rate of at least about 525 cubic centimeters per minute calculated according to the Tracer Gas Test and/or a Skin Hydration Value of less than about 18 grams per square meter per hour calculated according to a Skin Hydration Test set forth herein.
In another aspect, the present invention relates to a disposable absorbent article which comprises an absorbent, a front waist section, a rear waist section and an intermediate section which interconnects the front and rear waist sections. The absorbent article defines a Skin Hydration Value of less than about 18 grams per square meter per hour calculated according to the Skin Hydration Test set forth herein. In a particular embodiment, the absorbent article may define a Skin Hydration Value of less than about 15, desirably less than about 12 and more desirably less than about 10 grams per square meter per hour calculated according to the Skin Hydration Test. The absorbent article may further define a Wet Air Exchange Rate of at least about 190 cubic centimeters per minute and/or a Dry Air Exchange Rate of at least about 525 cubic centimeters per minute calculated according to the Tracer Gas Test as set forth herein.
In another aspect, the present invention relates to a disposable absorbent article which defines a front waist section, a rear waist section, and an intermediate section which interconnects the front and rear waist sections. The absorbent article includes a) a vapor permeable backsheet which defines a Water Vapor Transmission Rate of at least about 1000 grams per square meter per 24 hours calculated according to a Water Vapor Transmission Test as set forth herein; b) a liquid permeable topsheet which is positioned in facing relation with the backsheet; and c) an absorbent body located between the backsheet and the topsheet which may define multiple zones of high air permeability for improved air exchange. In a particular embodiment, the zones of high air permeability in the absorbent body define a Frazier Porosity which is at least about 10 percent greater than a Frazier Porosity of portions of the absorbent body adjacent to the zones of high air permeability. The absorbent article may further include a ventilation layer located between the backsheet and the absorbent body.
In still another aspect, the present invention relates to a disposable absorbent article which defines a front waist section, a rear waist section, and an intermediate section which interconnects the front and rear waist sections. The absorbent article includes a) a vapor permeable, liquid impermeable backsheet which defines a Water Vapor Transmission Rate of at least about 1000 grams per square meter per 24 hours calculated according to a Water Vapor Transmission Test as set forth herein; b) a liquid permeable topsheet which is positioned in facing relation with the backsheet, c) an absorbent body located between the backsheet and the topsheet; d) a ventilation layer located between the backsheet and the absorbent body; and e) a surge management layer located between the topsheet and the absorbent body. In a particular embodiment, the absorbent body of the absorbent article includes a plurality of zones of high air permeability for improved air exchange which define a Frazier Porosity which is at least about 10 percent greater than a Frazier Porosity of portions of the absorbent body adjacent to the zones.
In yet another aspect, the present invention relates to a disposable absorbent article which includes an absorbent, a front waist section, a rear waist section and an intermediate section which interconnects the front and rear waist sections. The absorbent article defines a C. albicans viability which is less than about 85 percent of the C. albicans viability of a control calculated according to a C. albicans Viability Test as set forth herein. In a particular embodiment, the C. albicans viability is less than about 80 percent and desirably less than about 60 percent of the C. albicans viability of the control calculated according to the C. albicans Viability Test. The absorbent article may further define a Wet Air Exchange Rate of at least about 190 cubic centimeters per minute and/or a Dry Air Exchange Rate of at least about 525 cubic centimeters per minute calculated according to the Tracer Gas Test as set forth herein and/or a Skin Hydration Value of less than about 18 grams per square meter per hour calculated according to the Skin Hydration Test set forth herein.
In another aspect, the present invention relates to a disposable absorbent article which comprises an absorbent, a front waist section, a rear waist section and an intermediate section which interconnects the front and rear waist sections. The absorbent article defines a Wet Skin Temperature/Dry Skin Temperature Ratio of no more than about 1.010 calculated according to a Skin Temperature Test as set forth herein. In particular embodiments, the absorbent article defines a Wet Skin Temperature/Dry Skin Temperature Ratio of no more than about 1.005, desirably no more than about 1.000, more desirably no more than about 0.995, and even more desirably no more than about 0.990 calculated according to the Skin Temperature Test. The absorbent article may further define a Wet Air Exchange Rate of at least about 190 cubic centimeters per minute and/or a Dry Air Exchange Rate of at least about 525 cubic centimeters per minute calculated according to the Tracer Gas Test as set forth herein and/or a Skin Hydration Value of less than about 18 grams per square meter per hour calculated according to the Skin Hydration Test set forth herein.
In still another aspect, the present invention resides in an absorbent article having a topsheet which includes a lotion formulation or treatment composition on the outer bodyfacing surface thereof. In a particular embodiment, the topsheet includes a lotion formulation comprising from about 5 to about 95 weight percent of an emollient, from about 5 to about 95 weight percent of a wax, and, optionally, from about 0.1 to about 25 weight percent of a viscosity enhancer. The lotion formulation may be applied by known methods in the art such as spraying, slot coating or printing to the topsheet at a temperature no more than about 10xc2x0 C. above a melting point of the lotion formulation to reduce migration of the lotion formulation on the topsheet.
In some embodiments, the emollient is selected from the group consisting of oils, esters, glycerol esters, ethers, alkoxylated carboxylic acids, alkoxylated alcohols, fatty alcohols and mixtures thereof. Moreover, in some embodiments, the wax is selected from the group consisting of animal based waxes, vegetable based waxes, mineral based waxes, silicone based waxes and mixtures thereof all of which may be natural or synthetic.
In a particular aspect, the lotion formulation includes from about 5 to about 95 weight percent of petrolatum, from about 5 to about 95 weight percent of a wax selected from the group consisting of animal based waxes, vegetable based waxes, mineral based waxes, silicone based waxes and mixtures thereof all of which may be natural or synthetic and from about 0.1 to about 25 weight percent of a polyolefin resin, all based on the total weight of the lotion formulation.
In still another aspect, the present invention resides in an absorbent article having a topsheet which includes a treatment composition on the outer bodyfacing surface thereof. The treatment composition includes a surfactant and a skin health benefit agent, preferably as an emulsion such as an oil-in-water emulsion. The skin health benefit agent may include zinc compositions. The treatment composition may also include a protein such as silk proteins like sericin.
The various aspects of the present invention advantageously provide an absorbent article with maintain or improve the health of the wearer""s skin. For example, such improved absorbent articles may exhibit substantially reduced levels of hydration of the wearer""s skin when in use compared to conventional absorbent articles. The reduced level of skin hydration promotes drier, more comfortable skin and renders the skin less susceptible to the viability-of microorganisms. Thus, wearer""s of absorbent articles made according to the present invention have reduced skin hydration and more constant skin temperatures in use which can lead to a reduction in the incidence of skin irritation and rash.
Moreover, in particular embodiments, the lotionized or treated topsheet provides a soft, smooth contact with the wearer""s skin and reduced levels of skin irritation. Moreover, because the lotion formulations applied to the topsheet are more stable and have a higher viscosity than conventional lotion formulations, particularly at higher temperatures, a greater percentage of the added lotion remains on the surface of the topsheet where it can readily contact and transfer to the wearer""s skin to provide the benefit. Further, if desired, a lower amount of the lotion formulation can be added to the topsheet to provide the same benefit at a lower cost due to the localization of the lotion at the surface of the topsheet. As a result, the skin of the wearers of the absorbent articles of the present invention may be less susceptible to rashes, abrasion and irritation.